When Carol Boruk of La Marque, Texas, saw Kevin Trudeau selling his book on a late-night infomercial in November, she was mesmerized.

Trudeau was good-looking, energetic and articulate, and talked about nonpharmaceutical remedies that could eradicate virtually any disease -- and that he said were being suppressed by the government and the drug industry.

Boruk, who suffered from allergies and recurring headaches, called the number on the screen and happily forked over $30 for a copy.

So have millions of others. For the past three weeks, the updated and expanded version of "Natural Cures 'They' Don't Want You to Know About," which Trudeau published himself, has been outsold only by "Harry Potter and the Half- Blood Prince," according to Nielsen BookScan.

The total number of copies purchased since last August is roughly 3 million, according to Trudeau's publishing company. The book has been on the New York Times list of best-selling how-to books for eight weeks and is now No. 1.

Trudeau, 42, a publishing novice, is not a doctor or scientist, and has had some run-ins with the law.

In the early '90s, he served two years in federal prison for credit card fraud. He was later sued by the Illinois attorney general over an alleged pyramid marketing scheme, and he has tangled twice with the Federal Trade Commission over claims that he made in infomercials for various alternative remedies.

Last year, the FTC barred him from selling products through infomercials. "Natural Cures" was able to skirt that rule because books are protected as free speech under the First Amendment, a lawyer for the agency said.

Some of the book's assertions have prompted some readers to declare it a fraud. "Nothing more than a latter-day snake oil salesman," D. Bellini of Grand Rapids, Mich., posted on Amazon.com. Officials at the New York State Consumer Protection Board also did not like the book. In early August the board issued a statement warning that "Natural Cures" is full of "empty promises."

"This book is exploiting and misleading people who are searching for cures to serious illnesses," Teresa Santiago, the board's chairwoman, said in the statement.

Boruk, the allergy sufferer in Texas, said the book was not entirely what she was expecting, but she found it "eye-opening" and says it has inspired her to discontinue several medications and make significant changes to her diet. "I've lost 30 pounds, never get headaches anymore, and hardly notice my allergies," she said.

Trudeau says those who would call him a fraud misunderstand him. In a telephone interview, he said he is preaching a holistic gospel he firmly believes in. "I can't remember the last time I was sick," he said, speaking after just returning from what he said was a 14-mile hike.

He noted that lawsuits filed by the trade commission and by Illinois had been settled out of court, and had not contained findings of wrongdoing. He called the prison time stemming from activities in his mid-20s a "youthful mistake."

"I changed my priority from making money to positively impacting people," said Trudeau, who lives in Ojai (Ventura County), a town popular with Hollywood producers and writers.

Trudeau has amassed millions from producing infomercials and from direct sales of products. Promotional materials he used in the mid-'90s boasted of a net worth of more than $200 million. Today, Trudeau says he does not know how much money he has, but it is "probably a lot." He said he owned 10 cars and dozens of houses and condominiums around the world.

Trudeau has been honing his marketing skills since he was in high school in the former mill town of Lynn, Mass. He started when he was 15 with a mail- order business on how to obtain loans. After high school, while working at a car dealership, Trudeau said he met the owner of a company called Memory Masters Institute. He said he loved how the program sharpened his mind. When Memory Masters offered him a job in Chicago, he jumped.

During that period, he falsified credit-card applications, charged a total of $122,000 and landed in prison. When he was released, Trudeau struck up a business partnership with his cellmate, Jules Lieb.

He and Lieb, who had been imprisoned for conspiracy to distribute cocaine, started working for Nutrition for Life, a seller of vitamin and nutritional supplements. The two, through their company Trudeau Marketing Group, sold supplements and skin care products and recruited other distributors.

David Bertrand, who worked with Trudeau from 1995 to 1997, said Trudeau, then 32, was by far the most successful distributor the company ever had. In the first year of Trudeau's alliance with Nutrition for Life, sales more than doubled.

But lawyers in the Illinois attorney general's office were not happy with what they were seeing. In its lawsuit against Trudeau Marketing Group, the office alleged that Trudeau and Lieb were operating a pyramid scheme.

Trudeau maintains that his work for Nutrition for Life, which was not named in the suit, was a legal marketing strategy, no different from Amway. In the settlement, Trudeau paid $10,000.

Critics contend Trudeau's book is misleading. The New York Consumer Protection Board noted this month that Herbert Ley, who is quoted in a promotional blurb, never read the book; he died in 2001. Ley, a commissioner for the Food and Drug Administration in the 1960s, made the quoted comment in the 1970s, and his name is misspelled on the book jacket.

Many alternative medicine experts agree with the core principles in "Natural Cures." But they, too, say Trudeau stretches the facts.

"There's enough truth in what he's saying that it gives him credibility with people who are looking for answers," said Dr. Dean Ornish, founder of the Preventive Medicine Research Institute in Sausalito. "But a lot of what he says is either nonsense or not proven through credible means."